Galaxy crash sparks biggest spiral

VLT/Galex image of NGC 6872 Galex revealed a wealth of new stars at the galaxy's outer reaches

Related Stories

Astronomers have spotted the largest known spiral galaxy - by accident.

A team was looking through data from the Galaxy Evolution Explorer (Galex) satellite for star-forming regions around a galaxy called NGC 6872.

But they were shocked to see a vast swathe of ultraviolet light from young stars, indicating that the galaxy is actually big enough to accommodate five of our Milky Way galaxies within it.

The find was reported at the American Astronomical Society meeting in the US.

NGC 6872, a galaxy about 212 million light-years away in the constellation Pavo, was already known to be among the largest spiral galaxies.

Near it sits a lens-shaped or lenticular galaxy called IC 4970, which appears to have crashed through the spiral in recent astronomical times.

Rafael Eufrasio of the Catholic University of America and Nasa's Goddard Space Flight Center and colleagues from the University of Sao Paulo in Brazil and the European Southern Observatory in Chile were interested in a number of regions away from the galaxy.

"I was not looking for the largest spiral - it just came as a gift," Mr Eufrasio told BBC News.

Galex - a space telescope designed to search for the ultraviolet light that newly born stars put out - hinted that NGC 6872 was made much larger in size by the collision.

The team went on to use data from a range of other telescopes including the Very Large Telescope, the Two Micron All-Sky Survey and the Spitzer space telescope - each of which sees in a particular set of colours, in turn evidencing stars of varying ages.

They found the youngest stars in the outer reaches of the galaxy's enormous spiral arms, getting progressively older toward the centre.

That suggests a wave of star formation that travelled down the arms, set off by the collision with IC 4970, with the newest stellar neighbourhoods pushing the galaxy into the top spot in terms of size.

"It's been known to be among the largest for two decades, but it's much larger than we thought," explained Mr Eufrasio.

"The galaxy that collided with the [central disc of NGC 6872] splashed stars all over the place - 500,000 light-years away."

A simulation of the galactic collision suggests it happened 130 million years ago A simulation of the galactic collision suggests it happened 130 million years prior to the situation we see today

Besides being one for the record books, NGC 6872 updates the catalogue of known galaxy smash-ups, demonstrating how dramatically galaxies can be changed and added to by collisions.

"It shows the evolution of galaxies in the larger context of the Universe - how the large galaxies we had before were accreted from small clumps in the early Universe," Mr Eufrasio said.

"We're just seeing one example of two interacting galaxies but in the past that happened much more often - that's how the big [spiral galaxy] discs we have were probably formed. Putting that in a larger context, it's a very cool system."


More on This Story

Related Stories

The BBC is not responsible for the content of external Internet sites


This entry is now closed for comments

Jump to comments pagination
  • rate this

    Comment number 71.

    Absolutely amazing. The distance is mind boggling by human scale. 212 million light years away is when dinosaurs ruled planet earth. If a human had been launched from here at the speed of light, thousands of generations later, his offsprings would have set foot on some planet in the galaxy now. Mmmmmm, what would the speed of light do to aging?? Mystery, mystery indeed. God......can take a break.

  • rate this

    Comment number 70.

    212 million light-years away?

    probably looks nothing like that photo today.

    ps - is that the milennium Falcon shooting across the gap between the Galaxies?

  • rate this

    Comment number 69.

    @53 - because some people assume that asking a question is the same as denying. You get people like this everywhere, they're effectively treating science as a religion, and don't seem to realise that the question is probably the most important tool that science has.
    (NB Just in case it's not clear, this comment is directed at the people that marked Jocky down, not at Jocky).

  • rate this

    Comment number 68.

    Any chance the rabid atheists could stop frothing at the mouth and not post random anti-religious posts on every single commented thread out there?

    Rabid atheists? Now thats what I call a small demographic - people who don't believe in a god and who have rabies. Shame the frothing is involuntary then, or I'm sure they'd glady comply. Maybe a miracle could help?

  • rate this

    Comment number 67.

    Why does something so incredible and majestic have to be appropriated by the Dawkins cult as an opportunity to post bile and childish vitriol about religion? Can't we all just stop and be amazed by this discovery, regardless of exactly how we think it might have come to pass?

    Yours, an agnostic theist scientist and engineer.

  • Comment number 66.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • Comment number 65.

    This comment was removed because the moderators found it broke the house rules. Explain.

  • rate this

    Comment number 64.

    """""religion hater
    Yet another leap forward science, leaving pointless religion in the dust where it belongs""""""

    Zero chance of religion dying out, just get used to it:-) Religion evolves, always has done, always will (as 'always' as the time left before this species goes extinct). Science only refutes (sometimes confirms) details of some past religious belief systems, the core just is.

  • rate this

    Comment number 63.


    No. Any organisation that legitimises ignorance, and tries to enforce belief without justification, reason or evidence is dangerous.

    It twists words written in a different time in a vain attempt to stunt human progress, and maintain it's unjustified position of power.

    But reason has a weapon: education. Slowly but surely, it's working, aided by fantastic discoveries like this.

  • rate this

    Comment number 62.

    This is awesome and *newsflash* has nothing to do with disproving or proving religion, it is simply scientific beauty & wonder in its own right. I do wish those making false assumptions about other people's beliefs while peddling their own dogmatic atheistic agenda would just pipe down & let the rest of us appreciate this scientific discovery for its own merits.

  • rate this

    Comment number 61.

    The universe. A great place of exciting and unexpected phenomenon. People say this shows how small our existance is but infact it is the opposite. Look at what elements occur the most in the universe, look at what is the most common in the human body. We were made from the elements created deep in the heart of stars. We are not part merely observing the universe, we are part of it....

  • rate this

    Comment number 60.

    When you think of the sheer size of the universe it makes you realise that there has to be life elsewhere, even if we never get to meet it.

  • rate this

    Comment number 59.

    this is where some turns to mysticism. you never get it right .always changes your established theories. well keep going. must go on.

  • rate this

    Comment number 58.

    Watching Stargazing Live, it showed how this kind of science is so accessible.

    Okay, so to deal with it fully you need to use brain melting maths, but if that is not your bag, you can still pick up a cheap telescope package, get into your garden with a hot flask of coffee and stare and learn.

    What a wonder!

  • rate this

    Comment number 57.

    Incredible stuff......the sheer size and scale of things out there is beyond my imagination!!! Truly amazing!

    We are discovering new things like this which are at the cutting edge and limits of our scientific knowledge....

    And people will still argue about contradictory ramblings written in books thousands of years ago........

    Personally I think Richard Dawkins should be Prime Minister!

  • rate this

    Comment number 56.

    The more we learn the more insignificant our ideals may become, pity we are all busy wrecking our world for money, religion and patches of land...

  • rate this

    Comment number 55.

    if the galaxy is 212 million light years is as it was during the great dying on earth which resulted in 80% of the worlds species being wiped out.incredible shows you how pathetic we are moaning about money and rubbish like that.

  • rate this

    Comment number 54.

    All we are, all we have made and all we fight about really is of no matter at all once you see just how big everything else is. I find this very reassuring.

  • rate this

    Comment number 53.

    26. Jocky B

    Not galaxy related, but in my opinion incredibly harsh that you had -5 ratings (when I wrote this) for asking a good question...

  • rate this

    Comment number 52.

    It's great to see science in headline news. Science and other tertiary subjects account for around 45% of our economy yet only 0.3% of the national budget is spent on science/R+D. To me this is an economic and scientific travesty. Science should be pushed onto the oublic from every angle. I would like to see the science budget doubled.


Page 28 of 31


More Science & Environment stories



Copyright © 2015 BBC. The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.